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Modulating opinion It might sound fishy, but US researchers say minnows make perfect lab rats when it comes to exploring the surprising power of the uninformed in group decision-making.

Research published today in the journal Science suggest individuals with no strong feelings about a given situation's outcome can dilute the influence of a powerful minority that would otherwise dominate.

In other words, thanks to the mighty minnow, it could be a scientific fact that apolitical individuals, when pressed for a decision, will shun the minority view - no matter how savvy, shrill or strident that view might be.

In the study, one group of fish was trained to associate the colour blue with a food reward. Another, smaller group was trained to do the same, but with the colour yellow.

Putting the two groups together found the minority calling the shots when it came to deciding to what colour the entire school would swim to collect their reward.

But then things changed when a few, untrained fish - representing what Couzin's team called the 'uninformed' segment of the piscine realm, with no preference for one colour or another - were added to the mix.

"As we added 'informed individuals' into the process, we can actually flip the group back to majority control," says Couzin.

"The uninformed individuals spontaneously support the majority view and effectively reduce the differences of intransigence between the two subsets."

The silent majority regains control

Running the result through mathematical models and computer simulations, the researchers found parallels with human behaviour that blew common assumptions about the power of outspoken minorities out of the water.

"We usually assume that a highly opinionated and forceful group is going to sway everyone," says Donald Saari of the University of California. "What we have here is something very different."

In a political context, it could explain why an hardline candidate or extremist party might do well in a US primary or British by-election, but stumble when 'uninformed' voters turn out en masse for a general election.

"The uninformed individuals effectively are promoting a democratic outcome," says Couzin, adding however that there are limits - as his researchers discovered back at the fish tank.

"As we keep adding 'uninformed individuals,' eventually 'noise' (confusion) dominates," he says. At that point, information of any kind is no longer shared effectively - and the whole group starts making decisions randomly.